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Determination of trace metals and analysis of arsenic species in tropical marine fishes from Spratly islands
Marine Pollution Bulletin xxx (xxxx) xxx–xxx
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Determination of trace metals and analysis of arsenic species in tropical marine fishes from Spratly islands Jingxi Lia,b,⁎, Chengjun Suna,c, Li Zhenga,d, Fenghua Jianga, Shuai Wanga, Zhixia Zhuanga,b, Xiaoru Wanga,b a
Marine Ecology Research Center, First Institute of Oceanography of State Oceanic Administration, Qingdao 266061, China Xiamen Huaxia University, Xiamen 361024, China c Laboratory of Marine Drugs and Bioproducts, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China d Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China b
A R T I C L E I N F O
A B S T R A C T
Keywords: Trace metals Tropical fishes Bioaccumulation Arsenic species Spratly islands
Trace metal contents in 38 species of tropical marine fishes harvested from the Spratly islands of China were determined by microwave digestion and inductively coupled plasma mass spectrometry analysis. Arsenic species were determined by high-performance liquid chromatography and inductively coupled plasma mass spectrometry analysis. The average levels of Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Pb, and U in the fish samples were 1.683, 0.350, 0.367, 2.954, 36.615, 0.087, 0.319, 1.566, 21.946, 20.845, 2.526, 3.583, 0.225, 0.140, and 0.061 mg·kg− 1, respectively; Fe, Zn, and As were found at high concentrations. The trace metals exhibited significant positive correlation between each other, with r value of 0.610–0.852. Further analysis indicated that AsB (8.560–31.020 mg·kg− 1) was the dominant arsenic species in the fish samples and accounted for 31.48% to 47.24% of the total arsenic. As(III) and As(V) were detected at low concentrations, indicating minimal arsenic toxicity.
Heavy metal pollution in marine environments is a serious environmental problem (Jambeck et al., 2015; Das et al., 2007; Naser, 2013). The accumulation of heavy metals in marine organisms may affect human health through the food chain (Zmozinski et al., 2013; Modibbo et al., 2014). Therefore, scholars have focused on heavy metal accumulation in seafood and fishes (Darko et al., 2016; Yang et al., 2014; Stankovic and Jovic, 2012). Fishes are often at the top of the aquatic food chain and accumulate large amounts of heavy metals from the marine environments (Mansour and Sidky, 2002; Low et al., 2015). The concentration and degree of heavy metal accumulation in fishes are affected by nutritional status, biological variables (e.g., species), and heavy metal concentrations in seawater and sediments. Moreover, the bioaccumulation of heavy metals can be used as an index of the pollution status of relevant seawater body to study the biological role of metals present at high levels in aquatic organisms, especially fish (Awheda et al., 2015; Authman et al., 2015; Omar et al., 2014). The Spratly islands, which are included in the major archipelagos in the South China Sea (Li et al., 2017), contain abundant fish resources. Approximately 2927 marine species exist in the Spratly island sea and include 524 marine fish species (Rosenberg and Stahlschmidt, 2011; Qiu et al., 2010). In recent years, tourism and the increasing
⁎
industrialization of neighboring countries have led to severe disruption of native flora and fauna, over-exploitation of natural resources, and environmental pollution (Mora et al., 2011; Dorman et al., 2016). Many activities adversely affect local marine organisms (Li et al., 2016). In this regard, the conservation of Spratly island ecosystems has gained increasing attention. However, limited information is available regarding trace metal content in fish harvested from the Spratly island seas. Metals, such as As, Cd, Hg, and Pb, are not essential and toxic even at trace levels, whereas V, Fe, Zn, Se, Co, Cu, and Mn are metals vital to biological systems (Abadi et al., 2015; Kalay and Canli, 2000). The levels of heavy metals in fish samples have been widely investigated because of their effects on human health. Moreover, the presence of several arsenic species in seafood has been increasingly studied because the toxicity of As depends its chemical species (Zhang et al., 2012); among As species, arsenobetaine (AsB) and arsenocholine (AsC) are considered nontoxic. Arsenic species, such as monomethylarsonic acid (MMA) and dimethylarsenic acid (DMA), are slightly toxic to humans, whereas inorganic species, such as arsenite [As(III)] and arsenate [As (V)], are the most toxic (Geng et al., 2009; Feldmann and Krupp, 2011; Leufroy et al., 2011; Zhang et al., 2016).
Corresponding author at: Marine Ecology Research Center, First Institute of Oceanography of State Oceanic Administration, Qingdao 266061, China. E-mail address: jxli@fio.org.cn (J. Li).
http://dx.doi.org/10.1016/j.marpolbul.2017.06.017 Received 2 May 2017; Received in revised form 23 May 2017; Accepted 6 June 2017 0025-326X/ © 2017 Published by Elsevier Ltd.
Please cite this article as: Li, J., Marine Pollution Bulletin (2017), http://dx.doi.org/10.1016/j.marpolbul.2017.06.017
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0.350–14.300 mg·kg− 1 for Mn, 13.400–146.700 mg·kg− 1 for Fe, 0.007–0.458 mg·kg− 1 for cobalt (Co), 0.029–3.234 mg·kg− 1 for nickel (Ni), 0.487–5.144 mg·kg− 1 for Cu, 8.662–54.520 mg·kg− 1 for Zn, 1.511–65.660 mg·kg− 1 for As, 0.964–4.959 mg·kg− 1 for Se, 0.027–39.420 mg·kg− 1 for Mo, 0.002–1.301 mg·kg− 1 for Cd, 0.012–0.769 mg·kg− 1 for Pb, and ND–0.415 mg·kg− 1 for U. The average range of trace metals followed the order of Fe > Zn > As > Mo > Mn > Se > Al > Cu > Cr > V > Ni > Cd > Pb > Co > U. The highest metal concentrations were found in Paraluteres prionurus Bleeker (Al, Cu, Zn, and Pb), Gobiidae (V), Pervagor melanocephalus (Cr), Brittle star (Mn, Co, Ni, Cd, and U), Gymnothorax reticularis Bloch (Fe), Cheilinus rhodochrous (As), and Gnathodentex aureolineatus (Se and Mo). The lowest concentrations of trace metals were as follows: 0.045 mg·kg− 1 Al, 13.400 mg·kg− 1 Fe, 0.002 mg·kg− 1 Cd, 0.012 mg·kg− 1 Pb, and 0.029 mg·kg− 1 Ni in Aluterus scriptus; 0.040 mg·kg− 1 V in Cypselurus katoptron; 0.122 mg·kg− 1 Cr and 0.007 mg·kg− 1 Co in T. quinquevittatum; 0.350 mg·kg− 1 Mn and 1.511 mg·kg− 1 As in Kyphosus lembus; 0.487 mg·kg− 1 Cu in O. meleagris; 8.662 mg·kg− 1 Zn in Sufflamen fraenatus; 0.964 mg·kg− 1 Se in C. striatus; and 0.027 mg·kg− 1 Mo in Lutjanus kasmira. The concentrations of V, Mn, Fe, Cu, Zn, and Cd are lower than the United States Environmental Protection Agency (USEPA) risk-based concentrations (V: 6.8 mg·kg− 1, Mn: 190 mg·kg− 1, Fe: 950 mg·kg− 1, Cu: 54 mg·kg− 1, Zn: 410 mg·kg− 1, and Cd: 1.4 mg·kg− 1). In some fishes, the concentrations of Co, As, and Se are slightly higher than the USEPA risk-based values (Co: 0.41 mg·kg− 1, As: 0.41 mg·kg− 1, and Se: 6.8 mg·kg− 1)(USEPA, 2010). The samples were compared with those collected from the Fisheries Research Institute at Chu-Pei (Taiwan), which is the designated reference site free from anthropogenic emissions; the reference samples possess the following: Mn: 0.3 mg·kg− 1, Cu: 0.3 mg·kg− 1, Zn: 12 mg·kg− 1, As: 0.1 mg·kg− 1, Se: 0.17 mg·kg− 1, and Pb: 0.04 mg·kg− 1 (Ling et al., 2009). The amounts of Mn, Cu, Zn, As, Se, and Pb in fish are higher than the base values. In particular, high As levels could be due to natural variations related to geographical origin. All trace metal distribution characteristics in fishes are shown in Fig. 1. The mean concentrations of Al, Mn, Fe, Zn, As, Se, and Mo were high. The normalized calculation results of all metal contents (Fig. 2) showed that Fe (39.26%), Zn (23.53%), and As (22.35%) exhibited the highest distribution ratios, and the total ratio of other elements was 14.86%. The correlation coefficient among the selected heavy metals is presented in Table 3. Significant positive correlations were obtained between Mn and V (r = 0.610), Fe and Al (r = 0.749), Co and Mn (r = 0.718), Ni and Mn/Co (r = 0.648 and 0.830), Cu and Al (r = 0.650), Zn and Mn/Fe (r = 0.625 and 0.612), Cd and Mn/Co/Ni (r = 0.780, 0.648 and 0.698), Pb and Al/Fe/Cd (r = 0.734, 0.697 and 0.664), and U and Ni (r = 0.852). This finding indicates the same or similar source input. Mo, As, and Se showed a negative correlation with the other metals. In the present study, a sequential procedure was used to extract different arsenic species to analyze the distribution pattern and levels of different arsenic species. The extraction process involved three steps, which produced three As fractions, namely, nonpolar (Asnonpolar) extracted by acetone, polar (Aspolar) extracted by methanol/H2O, and inorganic arsenic species (Asinorganic) extracted by 0.05 mol/L HCl. Arsenic species mainly included AsIII, AsV, MMA, DMA, AsB, and AsC. Speciation analysis of arsenic species was performed by HPLC-ICP-MS with deionized water and 50 mM (NH4)2CO3 as mobile phase. Six arsenic species were effectively and ideally separated under gradient elution (0–15 min linear gradient from 100%A to 100%B) by using mobile phase at low initial concentration and high elution rate (1.5 mL/
Heavy metal enrichment in aquaculture may pose a potential health risk. As such, we investigated and evaluated the levels of trace metals and arsenic species in fish samples collected from the Spratly island sea. This study mainly aims to: (1) test the total concentration of 15 trace metals in 38 species of tropical fishes, (2) evaluate the correlation and distribution characteristic of all trace metals, (3) explore differences in distribution pattern and levels of different arsenic species, and (4) assess the contamination degree of fish in the Spratly island sea area. This study is the first to analyze the content and distribution of trace metals and arsenic species in different tropical marine fishes in the Spratly island sea. Our study can provide initial data for further investigations on trace metals and health assessment of tropical marine lives in the Spratly islands. Therefore, thirty eight different species of fish were collected from the Spratly islands of China during a specific survey voyage in 2016. All alive fish species were frozen immediately and taken to laboratory under −20 °C after being identified. In the laboratory, all samples were firstly freeze-dried, ground, and sifted through an 80 mesh porous sieve before analysis. Then, approximately 0.5 g of sample was digested with 6 mL of 65% HNO3 (Merck) and 2 mL of concentrated H2O2 (Merck) in a microwave digestion system (CEM, digestion procedures in Table 1) and diluted to 25 mL by adding double deionized water. Blank digestion was also conducted through the same method. During test, the concentrations of Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Pb, and U were analyzed using an Agilent 7500a ICP-MS system with 50 μg·L− 1 Li, Sc, Ge, Y, In, Tb, and Bi (Agilent Technologies, USA) added online as internal standards to correct for matrix effects and instrumental drift. During test, the accuracy of microwave digestion/ICP-MS method was verified by analysis of certified reference materials (GBW10050 GSB-28, IGGE, China). The reference substance of shrimp tissue (GBW10050 GSB-28, IGGE, China) was treated and analyzed in the same way as all samples. The analysis results (Al: 273.6 mg·kg− 1, V: 0.22 mg·kg− 1, Cr: 0.36 mg·kg− 1, Mn: 8.12 mg·kg− 1, Fe: 103 mg·kg− 1, Co: 0.05 mg·kg− 1, Ni: 0.242 mg·kg− 1, Cu: 10.08 mg·kg− 1, Zn: 71 mg·kg− 1, As: 2.76 mg·kg− 1, Se: 5.32 mg·kg− 1, Mo: 0.04 mg·kg− 1, Cd: 0.036 mg·kg− 1, Pb: 0.187 mg·kg− 1, and U:0.0089 mg·kg− 1) are consistent with the certified values (Al: 290.0 mg·kg− 1, V: 0.24 mg·kg− 1, Cr: 0.35 mg·kg− 1, Mn: 8.9 mg·kg− 1, Fe: 112 mg·kg− 1, Co: 0.044 mg·kg− 1, Ni: 0.23 mg·kg− 1, Cu: 10.3 mg·kg− 1, Zn: 76 mg·kg− 1, As: 2.5 mg·kg− 1, Se: 5.1 mg·kg− 1, Mo: 0.037 mg·kg− 1, Cd: 0.039 mg·kg− 1, Pb: 0.20 mg·kg− 1, and U: 0.0097 mg·kg− 1 of dry weight). The results for standard reference substance showed that element recovery ranged from 91.24% to 113.64% (n = 3). The standard deviation was less than 6%, proving the good repeatability of the methods. Information about trace element concentrations in fish species is important for both environmental management and human consumption. The concentrations of trace metals in fish species collected from the Spratly islands are illustrated in Table 2. The contents of trace metals in all fish samples were as follows: 0.045–6.393 mg·kg− 1 for Al, 0.040–3.312 mg·kg− 1 for V, 0.122–0.947 mg·kg− 1 for Cr, Table 1 The working parameters of microwave digestion. Stage
1 2 3 4
Power/W
Temperature
Ramp
Hold
Max
%
T/°C
t/min
t/min
1500 1500 1500 1500
100 100 100 100
100 150 170 190
3:00 7:00 5:00 5:00
3:00 3:00 3:00 10:00
2
Al
1.284 1.460 2.707 2.006 1.569 2.057 1.176 1.478 1.883 2.370 3.109 1.539 0.420 2.492 1.381 6.393 1.036 1.833 1.099 1.172 1.083 1.736 2.112 2.558 1.553 1.106 1.486 0.045 1.181 1.387 1.447 1.602 1.749 2.740 1.186 0.366 1.478 0.666 1.683 0.045 6.393
Fish species
Ostracion meleagris Cephalopholis argus Monotaxis grandoculis Balistapus undulatus Cephalopholis urodelus Kyphosus lembus Parupeneus multifasciatus Epinephelus merra Bloch Parupeneus pleurostigma Melichthys vidua Pervagor melanocephalus Cheilinus fasciatus Cheilinus rhodochrous Cephalopholis sonnerati Myrispristis pralinius Paraluteres prionurus Bleeker Odonus niger Cypselurus katoptron Heteropriaccmthuscruentatus Sufflamen fraenatus Gnathodentex aureolineatus Myrispristis Linnaeus Epinephelus hexagonatus Coris gaimard Scarus forsteri Diodon hystrix Aluterus scriptus Parupeneus trifasciatus Brittle star Epinephelus, groupers Lutjanus kasmira Cephalopholis urodelus Gymnothorax reticularis Bloch Gobiidae Platax teira Ctenochaetus striatus Halassoma quinquevittatus Mean concentration Min concentration Max concentration
Table 2 Concentrations of trace metals in fishes (mg·kg− 1).
0.083 0.097 0.327 0.116 0.079 0.082 0.132 0.705 0.083 0.643 1.675 0.270 0.180 0.184 0.064 1.649 0.074 0.040 0.066 0.835 0.219 0.103 0.082 0.062 0.092 0.081 0.205 0.071 0.049 0.704 0.048 0.052 0.057 0.103 3.312 0.062 0.064 0.536 0.350 0.040 3.312
V 0.343 0.508 0.388 0.326 0.358 0.276 0.292 0.352 0.375 0.636 0.947 0.285 0.253 0.415 0.373 0.305 0.371 0.372 0.667 0.337 0.358 0.794 0.344 0.252 0.414 0.279 0.378 0.204 0.411 0.132 0.297 0.365 0.417 0.233 0.242 0.169 0.343 0.122 0.367 0.122 0.947
Cr 0.647 0.371 2.193 3.223 0.734 0.350 1.350 2.430 0.649 7.071 5.158 10.960 1.780 0.966 0.505 11.740 4.075 1.001 1.045 0.598 0.719 1.121 1.827 1.014 1.472 2.845 2.020 0.450 0.581 14.300 0.565 1.496 0.587 5.838 10.380 0.373 1.421 8.390 2.954 0.350 14.300
Mn 18.670 20.780 49.360 43.850 24.610 23.060 37.630 29.240 33.240 33.230 67.780 51.100 15.890 36.650 21.660 125.600 34.200 35.390 19.160 23.580 25.740 30.700 52.920 50.080 27.050 24.290 27.340 13.400 20.080 30.770 25.860 21.360 26.170 146.700 51.880 14.500 26.640 31.200 36.615 13.400 146.700
Fe 0.110 0.010 0.022 0.045 0.019 0.022 0.070 0.115 0.032 0.091 0.177 0.394 0.041 0.030 0.019 0.129 0.024 0.023 0.007 0.020 0.019 0.115 0.388 0.033 0.058 0.096 0.057 0.015 0.020 0.458 0.028 0.084 0.017 0.032 0.260 0.014 0.071 0.134 0.087 0.007 0.458
Co 0.051 0.145 0.152 0.074 0.063 0.049 0.287 0.392 0.154 0.193 0.305 0.474 0.178 0.268 0.082 0.568 0.078 0.086 0.033 0.157 0.103 0.522 1.441 0.093 0.169 0.173 0.154 0.029 0.107 3.234 0.080 0.364 0.088 0.089 1.117 0.052 0.124 0.406 0.319 0.029 3.234
Ni 0.487 0.802 1.185 1.553 1.773 1.549 1.340 1.585 1.930 2.288 2.829 2.375 1.344 2.126 0.825 5.144 1.592 2.453 0.745 1.004 2.597 0.962 1.890 1.098 0.828 1.162 1.706 0.876 0.857 0.601 2.295 0.955 1.572 1.063 1.590 0.983 0.851 2.692 1.566 0.487 5.144
Cu 18.690 10.000 41.760 16.170 12.690 33.860 30.780 22.540 11.810 52.680 37.310 42.340 18.360 13.840 9.126 54.520 21.050 15.830 8.679 8.662 9.525 15.350 12.840 15.380 19.110 12.610 36.160 12.740 8.792 15.890 8.902 19.430 11.790 46.770 31.160 16.160 12.350 48.280 21.946 8.662 54.520
Zn 2.211 2.284 37.600 23.990 24.980 1.511 54.820 36.290 27.420 31.830 16.830 5.522 65.660 15.240 9.330 7.924 17.980 8.482 4.288 58.570 45.820 26.270 15.890 4.052 22.020 2.601 57.250 30.470 19.210 2.311 19.850 6.334 4.218 9.459 4.766 8.931 1.704 58.180 20.845 1.511 65.660
As 2.826 3.208 2.243 2.848 3.168 4.009 2.369 3.048 2.190 2.517 2.141 3.571 2.093 2.718 3.852 2.480 2.765 2.187 2.942 2.699 4.959 1.951 3.848 2.815 2.405 1.135 1.312 2.698 1.914 0.993 2.285 1.523 3.278 1.680 1.989 2.553 0.964 1.802 2.526 0.964 4.959
Se 0.168 0.709 8.538 0.180 27.290 0.046 15.500 0.772 0.088 0.072 0.634 0.253 0.263 0.141 5.522 0.455 0.490 0.041 0.561 9.967 39.420 0.592 0.505 0.171 1.148 0.435 0.933 0.235 0.539 1.226 5.482 0.027 11.610 0.517 0.340 0.549 0.664 0.054 3.583 0.027 39.420
Mo 0.021 0.029 0.033 0.037 0.231 0.016 0.110 0.272 0.126 0.329 0.424 0.452 0.077 0.333 0.048 1.061 0.102 0.082 0.012 0.045 0.046 0.316 0.429 0.337 0.078 0.047 0.202 0.002 0.030 1.301 0.366 0.022 0.037 0.072 0.281 0.008 0.076 1.066 0.225 0.002 1.301
Cd 0.024 0.024 0.357 0.038 0.065 0.039 0.090 0.255 0.052 0.077 0.382 0.156 0.026 0.183 0.061 0.769 0.026 0.055 0.022 0.043 0.037 0.348 0.236 0.156 0.077 0.051 0.060 0.012 0.025 0.463 0.355 0.067 0.081 0.355 0.223 0.067 0.101 0.086 0.146 0.012 0.769
Pb
0.053 0.053 0.057 0.051 0.053 0.053 0.063 0.015 0.053 0.058 0.079 0.008 0.010 0.061 0.053 0.014 0.052 0.051 0.052 0.052 0.052 0.068 0.058 < DL 0.063 0.060 0.053 < DL 0.051 0.415 0.054 0.058 0.052 < DL 0.127 < DL 0.066 0.016 0.061 < DL 0.415
U
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hydrochloric (0.05 mM HCl) acid solution was used for extracting inorganic arsenicals by using the method reported by Mir (Mir et al., 2007). Extraction efficiency was evaluated by calculating the ratio between total arsenic present in the extracts and the total arsenic present in the sample TORT-2 (Table 4). The extraction efficiencies obtained in this work were 95.51%, 93.75%, 94.05%, 90.32%, and 87.24% for As(V), MMA, DMA, AsB, and AsC, respectively. Fig. 4 shows the distribution characteristics of arsenic species in fishes. AsB exhibited the highest concentration and ratio among all arsenic species. Fifteen fish samples were selected and analyzed for their content of As species (Table 4). AsB was found to be the main arsenic species in all fish samples; this species (8.560 mg·kg− 1 to 31.020 mg·kg− 1) accounted for 31.48% to 47.24% of the total arsenic species. MMA and DMA were detected as minor compounds, with contents of 2.43%–12.56% and 3.42%–12.16%, respectively. The contents of MMA and DMA are higher than those of As(III) and As(V) in fish samples; this finding is consistent with those reported by other published studies. In the present study, high AsB concentration was found in C. rhodochrous sample (47.24%), and high MMA/DMA content was observed in Balistapus undulatus sample (12.56% and 12.16%). The inorganic arsenic was identified and quantified as As(III) and As (V). As(III) was found in 40% of all samples being not detected. As(V) in all fish samples was below 3.3% of the total arsenic. The low concentrations of inorganic arsenic in fish samples are consistent with the findings of previous studies (Larsen et al., 2005; Fontcuberta et al., 2011). In conclusion, this work described the determination and distribution characteristics of trace metals and arsenic species in tropical marine fishes collected from the Spratly islands. The metal contents are lower than the USEPA risk-based concentrations. In particular, the distribution ratios of Fe, Zn, and As in the fish samples are high. The selected heavy metals exhibit significant positive correlations, indicating similar source input in the region. Analysis of arsenic species showed that AsB was the main species in the fish samples; hence, arsenic toxicity in all fishes was small with high-total concentration. The results can provide initial data for environmental behavior study of trace metals and health assessment in tropical organisms.
Fig. 1. The distribution of trace metal in fishes.
min). This method optimized Brisbin's method and can completely separate As(III), As(V), DMA, and MMA, but not AsB and AsC. As shown in Fig. 3, As(III), As(V), DMA, MMA, AsB, and AsC can be completely separated within 15 min. The As concentrations in 15 fishes of 38 samples are higher than 20.0 mg·kg− 1 (Table 4). The high As concentration in fishes may cause health hazards, although As usually exists in living organisms in different forms. As species show different levels of toxicity in the following order: As(V) > As(III) > (MMA) > (DMA) > (AsC) > (AsB), with LD50 values of 14, 20, 700–1800, 700–2600, 6500, and > 10,000) mg·kg− 1, respectively, in rats. The USEPA (USEPA, 2000) also advocated inorganic As uptake, instead of total As exposure, for assessment of human health risk. Inorganic As represented a minimal portion, accounting for less than 10% of total As in most cases (Huang et al., 2003). Hence, individual arsenic species must be considered to accurately evaluate their risk profiles. Thus, analysis of As species in marine organisms is important. The content and distribution of arsenic species in 15 fishes were analyzed. First, a sequential extraction procedure was used to fractionate arsenic compounds in dry fish samples. Other researchers usually ignored nonpolar arsenicals because of their low concentrations. In the present study, acetone exhibited the optimal performance in step I and was chosen as solvent in further experiments. The methanol or its water solution was the appropriate choice for water-soluble arsenicals in step II. In the last step, the diluted
Acknowledgements The authors gratefully acknowledge the Basic Scientific Fund for National Public Research Institutes of China (2016Q02 & 2017Q09) and The National Natural Science Foundation of China-Shandong Joint Funded Project (U1406403). C. Sun would also like to thank Taishan Scholar for funding support. Fig. 2. The comparison of the relative content of heavy metals.
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Table 3 The correlation coefficient of trace metal in fishes.
Al V Cr Mn Fe Co Ni Cu Zn As Se Mo Cd Pb U
Al
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
As
Se
Mo
Cd
Pb
U
1.000
0.310 1.000
0.237 0.073 1.000
0.347 0.610 (0.193) 1.000
0.749 0.355 (0.015) 0.501 1.000
0.100 0.393 (0.117) 0.718 0.201 1.000
0.065 0.350 (0.207) 0.648 0.111 0.830 1.000
0.650 0.386 0.066 0.417 0.488 0.141 (0.015) 1.000
0.502 0.410 (0.007) 0.625 0.612 0.244 0.045 0.521 1.000
(0.252) (0.027) (0.057) (0.127) (0.168) (0.198) (0.159) 0.121 0.156 1.000
0.007 (0.147) 0.063 (0.277) (0.112) (0.109) (0.239) 0.164 (0.166) (0.021) 1.000
(0.107) (0.090) (0.028) (0.224) (0.124) (0.211) (0.126) 0.121 (0.201) 0.325 0.471 1.000
0.385 0.389 (0.170) 0.780 0.337 0.648 0.698 0.505 0.416 0.003 (0.233) (0.147) 1.000
0.734 0.462 0.073 0.580 0.697 0.428 0.475 0.502 0.445 (0.167) (0.219) (0.126) 0.664 1.000
(0.087) 0.207 (0.164) 0.461 (0.055) 0.529 0.852 (0.291) (0.139) (0.260) (0.345) (0.040) 0.466 0.300 1.000
Note: “( )” mean negative correlation.
Fig. 3. The separation of arsenic species standard (10 μg/L AsC, AsB, AsIII, DMA, MMA and AsV mix solution).
Table 4 The concentration of arsenic species in different fish (mg·kg− 1, dry weight). Sample name TORT-2
Total As
As(III)
As(V)
MMA
DMA
AsB
AsC
a
21.6 ± 1.8
0.024 ± 0.010
14.25 ± 1.08
0.0928 ± 0.0371
0.84 ± 0.10
0.093 ± 0.069
0.0928 ± 0.0371
b
20.4 ± 1.3
ND
13.61 ± 1.05
0.087 ± 0.014
0.79 ± 0.21
0.084 ± 0.03
0.0807 ± 0.023
94.44
ND
95.51
93.75
94.05
90.32
87.24
22.02 23.99 24.98 26.27 27.42 30.47 31.83 36.29 37.60 45.82 54.82 57.25 58.18 58.57 65.66
ND ND ND ND ND 0.011 0.015 0.020 ND 0.031 0.029 0.018 0.090 0.018 0.022
0.560 0.432 0.212 0.185 0.110 0.301 0.410 0.201 0.289 1.011 1.211 0.895 0.932 0.247 0.331
2.360 3.012 2.220 1.960 3.230 1.965 2.011 1.656 0.995 2.831 3.010 2.089 1.977 1.423 4.012
2.101 2.916 1.987 2.031 2.590 2.461 2.236 2.011 1.985 3.004 3.612 2.886 2.501 2.005 3.678
8.560 9.231 10.011 11.320 9.650 10.988 10.021 12.110 14.530 15.091 21.360 24.025 25.371 26.003 31.020
0.240 0.307 ND ND ND ND ND ND ND 0.985 1.013 0.889 1.022 0.961 1.009
Reference Measured
Recovery (%) Coris gaimard Balistapus undulatus Cephalopholis urodelus Myrispristis Parupeneus pleurostigma Aluterus scriptus Melichthys vidua Epinephelus merra Bloch Monotaxis grandoculis Gnathodentex aureolineatus Parupeneus multifasciatus Diodon hystrix Halassoma quinquevittatus Sufflamen fraenatus Cheilinus rhodochrous a b
These were reference value given by Raimund Wahlen (Wahlen and McSheehy, 2004). Determination of arsenic species by HPLC-ICP-MS in the study.
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Fig. 4. The analysis of arsenic species in fishes.
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References Abadi, D.R., Dobaradaran, S., Nabipour, I., Lamani, X., Ravanipour, M., Tahmasebi, R., Nazmara, S., 2015. Comparative investigation of heavy metal, trace, and macro element contents in commercially valuable fish species harvested off from the Persian Gulf. Environ. Sci. Pollut. Res. Int. 22 (9), 6670–6678. Authman, M.M.N., Zaki, M.S., Khallaf, E.A., Abbas, H.H., 2015. Use of fish as bio-indicator of the effects of heavy metals pollution. Journal of Aquaculture Research & Development 4 (6), 1–13. Awheda, I., Ahmed, A., Fahej, M., Elwahaishi, S., Smida, F., 2015. Fish as bioindicators of heavy metals pollution in marine environments: a review. Indian Journal of Appoede Research 5 (8), 379–384. Darko, G., Azanu, D., Logo, N.K., 2016. Accumulation of toxic metals in fish raised from sewage-fed aquaculture and estimated health risks associated with their consumption. Cogent Environmental Science 1 (2), 1–12. Das, S., Shanmugapriya, R., Lyla, P.S., Khan, S.A., 2007. Heavy metal tolerance of marine bacteria-an index of marine pollution. National Academy Science Letters 30 (9), 279–284. Dorman, J.G., Castruccio, F.S., Curchitser, E.N., Kleypas, J.A., Powell, T.M., 2016. Modeled connectivity of Acropora millepora populations from reefs of the Spratly Islands and the greater South China Sea. Coral Reefs 35 (1), 1–11. Feldmann, J., Krupp, E.M., 2011. Critical review or scientific opinion paper: Arsenosugars-a class of benign arsenic species or justification for developing partly speciated arsenic fractionation in foodstuffs? Anal. Bioanal. Chem. 399 (5), 1735–1741. Fontcuberta, M., Calderon, J., Villalbí, J.R., Centrich, F., Portaña, S., Espelt, A., Duran, J., Nebot, M., 2011. Total and inorganic arsenic in marketed food and associated health risks for the Catalan (Spain) population. J. Agric. Food Chem. 59 (18), 10013–10022. Geng, W., Komine, R., Ohta, T., Nakajima, T., Takanashi, H., Ohki, A., 2009. Arsenic speciation in marine product samples: comparison of extraction-HPLC method and digestion-cryogenic trap method. Talanta 79 (2), 369–375. Huang, Y.K., Lin, K.H., Chen, H.W., Chang, C.C., Liu, C.W., Yang, M.H., et al., 2003. Arsenic species contents at aquaculture farm and in farmed mouthbreeder (Oreochromis mossambicus) in blackfoot disease hyperendemic areas. Food Chem. Toxicol. 41 (11), 1491–1500. Jambeck, J.R., Geyer, R., Wilcox, C., Siegler, T.R., Perryman, M., Andrady, A., Narayan, R., Law, K.L., 2015. Marine pollution. Plastic waste inputs from land into the ocean. Science 347 (6223), 768–771. Kalay, M., Canli, M., 2000. Elimination of essential (Cu, Zn) and non-nssential (Cd, Pb) metals from tissues of a freshwater fish Tilapia zilli. Turkish Journal of Zoology 24 (4), 429–436. Larsen, E.H., Engman, J., Sloth, J.J., Hansen, M., Jorhem, L., 2005. Determination of inorganic arsenic in white fish using microwave-assisted alkaline alcoholic sample dissolution and HPLC-ICP-MS. Anal. Bioanal. Chem. 381 (2), 339–346. Leufroy, A., Noël, L., Dufailly, V., Beauchemin, D., Guérin, T., 2011. Determination of seven arsenic species in seafood by ion exchange chromatography coupled to inductively coupled plasma-mass spectrometry following microwave assisted extraction: method validation and occurrence data. Talanta 83 (3), 770–779. Li, J.X., Sun, C.J., Li, Zheng, Yin, X.F., Chen, J.H., Jiang, F.H., 2017. Geochemical characteristics of rare earth elements in the surface sediments from the Spratly Islands of China. Mar. Pollut. Bull. 114 (2), 1103–1109. Li, Y., Zhang, J., Zhang, R., Song, P.Q., Zhong, Z.H., Wang, Y.P., Lin, L.S., 2016. Fish diversity in southwestern seas of Nansha Islands and the mouth of Beibu Bay.
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Determination of trace metals and analysis of arsenic species in tropical marine fishes from Spratly islands Jingxi Lia,b,⁎, Chengjun Suna,c, Li Zhenga,d, Fenghua Jianga, Shuai Wanga, Zhixia Zhuanga,b, Xiaoru Wanga,b a
Marine Ecology Research Center, First Institute of Oceanography of State Oceanic Administration, Qingdao 266061, China Xiamen Huaxia University, Xiamen 361024, China c Laboratory of Marine Drugs and Bioproducts, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China d Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China b
A R T I C L E I N F O
A B S T R A C T
Keywords: Trace metals Tropical fishes Bioaccumulation Arsenic species Spratly islands
Trace metal contents in 38 species of tropical marine fishes harvested from the Spratly islands of China were determined by microwave digestion and inductively coupled plasma mass spectrometry analysis. Arsenic species were determined by high-performance liquid chromatography and inductively coupled plasma mass spectrometry analysis. The average levels of Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Pb, and U in the fish samples were 1.683, 0.350, 0.367, 2.954, 36.615, 0.087, 0.319, 1.566, 21.946, 20.845, 2.526, 3.583, 0.225, 0.140, and 0.061 mg·kg− 1, respectively; Fe, Zn, and As were found at high concentrations. The trace metals exhibited significant positive correlation between each other, with r value of 0.610–0.852. Further analysis indicated that AsB (8.560–31.020 mg·kg− 1) was the dominant arsenic species in the fish samples and accounted for 31.48% to 47.24% of the total arsenic. As(III) and As(V) were detected at low concentrations, indicating minimal arsenic toxicity.
Heavy metal pollution in marine environments is a serious environmental problem (Jambeck et al., 2015; Das et al., 2007; Naser, 2013). The accumulation of heavy metals in marine organisms may affect human health through the food chain (Zmozinski et al., 2013; Modibbo et al., 2014). Therefore, scholars have focused on heavy metal accumulation in seafood and fishes (Darko et al., 2016; Yang et al., 2014; Stankovic and Jovic, 2012). Fishes are often at the top of the aquatic food chain and accumulate large amounts of heavy metals from the marine environments (Mansour and Sidky, 2002; Low et al., 2015). The concentration and degree of heavy metal accumulation in fishes are affected by nutritional status, biological variables (e.g., species), and heavy metal concentrations in seawater and sediments. Moreover, the bioaccumulation of heavy metals can be used as an index of the pollution status of relevant seawater body to study the biological role of metals present at high levels in aquatic organisms, especially fish (Awheda et al., 2015; Authman et al., 2015; Omar et al., 2014). The Spratly islands, which are included in the major archipelagos in the South China Sea (Li et al., 2017), contain abundant fish resources. Approximately 2927 marine species exist in the Spratly island sea and include 524 marine fish species (Rosenberg and Stahlschmidt, 2011; Qiu et al., 2010). In recent years, tourism and the increasing
⁎
industrialization of neighboring countries have led to severe disruption of native flora and fauna, over-exploitation of natural resources, and environmental pollution (Mora et al., 2011; Dorman et al., 2016). Many activities adversely affect local marine organisms (Li et al., 2016). In this regard, the conservation of Spratly island ecosystems has gained increasing attention. However, limited information is available regarding trace metal content in fish harvested from the Spratly island seas. Metals, such as As, Cd, Hg, and Pb, are not essential and toxic even at trace levels, whereas V, Fe, Zn, Se, Co, Cu, and Mn are metals vital to biological systems (Abadi et al., 2015; Kalay and Canli, 2000). The levels of heavy metals in fish samples have been widely investigated because of their effects on human health. Moreover, the presence of several arsenic species in seafood has been increasingly studied because the toxicity of As depends its chemical species (Zhang et al., 2012); among As species, arsenobetaine (AsB) and arsenocholine (AsC) are considered nontoxic. Arsenic species, such as monomethylarsonic acid (MMA) and dimethylarsenic acid (DMA), are slightly toxic to humans, whereas inorganic species, such as arsenite [As(III)] and arsenate [As (V)], are the most toxic (Geng et al., 2009; Feldmann and Krupp, 2011; Leufroy et al., 2011; Zhang et al., 2016).
Corresponding author at: Marine Ecology Research Center, First Institute of Oceanography of State Oceanic Administration, Qingdao 266061, China. E-mail address: jxli@fio.org.cn (J. Li).
http://dx.doi.org/10.1016/j.marpolbul.2017.06.017 Received 2 May 2017; Received in revised form 23 May 2017; Accepted 6 June 2017 0025-326X/ © 2017 Published by Elsevier Ltd.
Please cite this article as: Li, J., Marine Pollution Bulletin (2017), http://dx.doi.org/10.1016/j.marpolbul.2017.06.017
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0.350–14.300 mg·kg− 1 for Mn, 13.400–146.700 mg·kg− 1 for Fe, 0.007–0.458 mg·kg− 1 for cobalt (Co), 0.029–3.234 mg·kg− 1 for nickel (Ni), 0.487–5.144 mg·kg− 1 for Cu, 8.662–54.520 mg·kg− 1 for Zn, 1.511–65.660 mg·kg− 1 for As, 0.964–4.959 mg·kg− 1 for Se, 0.027–39.420 mg·kg− 1 for Mo, 0.002–1.301 mg·kg− 1 for Cd, 0.012–0.769 mg·kg− 1 for Pb, and ND–0.415 mg·kg− 1 for U. The average range of trace metals followed the order of Fe > Zn > As > Mo > Mn > Se > Al > Cu > Cr > V > Ni > Cd > Pb > Co > U. The highest metal concentrations were found in Paraluteres prionurus Bleeker (Al, Cu, Zn, and Pb), Gobiidae (V), Pervagor melanocephalus (Cr), Brittle star (Mn, Co, Ni, Cd, and U), Gymnothorax reticularis Bloch (Fe), Cheilinus rhodochrous (As), and Gnathodentex aureolineatus (Se and Mo). The lowest concentrations of trace metals were as follows: 0.045 mg·kg− 1 Al, 13.400 mg·kg− 1 Fe, 0.002 mg·kg− 1 Cd, 0.012 mg·kg− 1 Pb, and 0.029 mg·kg− 1 Ni in Aluterus scriptus; 0.040 mg·kg− 1 V in Cypselurus katoptron; 0.122 mg·kg− 1 Cr and 0.007 mg·kg− 1 Co in T. quinquevittatum; 0.350 mg·kg− 1 Mn and 1.511 mg·kg− 1 As in Kyphosus lembus; 0.487 mg·kg− 1 Cu in O. meleagris; 8.662 mg·kg− 1 Zn in Sufflamen fraenatus; 0.964 mg·kg− 1 Se in C. striatus; and 0.027 mg·kg− 1 Mo in Lutjanus kasmira. The concentrations of V, Mn, Fe, Cu, Zn, and Cd are lower than the United States Environmental Protection Agency (USEPA) risk-based concentrations (V: 6.8 mg·kg− 1, Mn: 190 mg·kg− 1, Fe: 950 mg·kg− 1, Cu: 54 mg·kg− 1, Zn: 410 mg·kg− 1, and Cd: 1.4 mg·kg− 1). In some fishes, the concentrations of Co, As, and Se are slightly higher than the USEPA risk-based values (Co: 0.41 mg·kg− 1, As: 0.41 mg·kg− 1, and Se: 6.8 mg·kg− 1)(USEPA, 2010). The samples were compared with those collected from the Fisheries Research Institute at Chu-Pei (Taiwan), which is the designated reference site free from anthropogenic emissions; the reference samples possess the following: Mn: 0.3 mg·kg− 1, Cu: 0.3 mg·kg− 1, Zn: 12 mg·kg− 1, As: 0.1 mg·kg− 1, Se: 0.17 mg·kg− 1, and Pb: 0.04 mg·kg− 1 (Ling et al., 2009). The amounts of Mn, Cu, Zn, As, Se, and Pb in fish are higher than the base values. In particular, high As levels could be due to natural variations related to geographical origin. All trace metal distribution characteristics in fishes are shown in Fig. 1. The mean concentrations of Al, Mn, Fe, Zn, As, Se, and Mo were high. The normalized calculation results of all metal contents (Fig. 2) showed that Fe (39.26%), Zn (23.53%), and As (22.35%) exhibited the highest distribution ratios, and the total ratio of other elements was 14.86%. The correlation coefficient among the selected heavy metals is presented in Table 3. Significant positive correlations were obtained between Mn and V (r = 0.610), Fe and Al (r = 0.749), Co and Mn (r = 0.718), Ni and Mn/Co (r = 0.648 and 0.830), Cu and Al (r = 0.650), Zn and Mn/Fe (r = 0.625 and 0.612), Cd and Mn/Co/Ni (r = 0.780, 0.648 and 0.698), Pb and Al/Fe/Cd (r = 0.734, 0.697 and 0.664), and U and Ni (r = 0.852). This finding indicates the same or similar source input. Mo, As, and Se showed a negative correlation with the other metals. In the present study, a sequential procedure was used to extract different arsenic species to analyze the distribution pattern and levels of different arsenic species. The extraction process involved three steps, which produced three As fractions, namely, nonpolar (Asnonpolar) extracted by acetone, polar (Aspolar) extracted by methanol/H2O, and inorganic arsenic species (Asinorganic) extracted by 0.05 mol/L HCl. Arsenic species mainly included AsIII, AsV, MMA, DMA, AsB, and AsC. Speciation analysis of arsenic species was performed by HPLC-ICP-MS with deionized water and 50 mM (NH4)2CO3 as mobile phase. Six arsenic species were effectively and ideally separated under gradient elution (0–15 min linear gradient from 100%A to 100%B) by using mobile phase at low initial concentration and high elution rate (1.5 mL/
Heavy metal enrichment in aquaculture may pose a potential health risk. As such, we investigated and evaluated the levels of trace metals and arsenic species in fish samples collected from the Spratly island sea. This study mainly aims to: (1) test the total concentration of 15 trace metals in 38 species of tropical fishes, (2) evaluate the correlation and distribution characteristic of all trace metals, (3) explore differences in distribution pattern and levels of different arsenic species, and (4) assess the contamination degree of fish in the Spratly island sea area. This study is the first to analyze the content and distribution of trace metals and arsenic species in different tropical marine fishes in the Spratly island sea. Our study can provide initial data for further investigations on trace metals and health assessment of tropical marine lives in the Spratly islands. Therefore, thirty eight different species of fish were collected from the Spratly islands of China during a specific survey voyage in 2016. All alive fish species were frozen immediately and taken to laboratory under −20 °C after being identified. In the laboratory, all samples were firstly freeze-dried, ground, and sifted through an 80 mesh porous sieve before analysis. Then, approximately 0.5 g of sample was digested with 6 mL of 65% HNO3 (Merck) and 2 mL of concentrated H2O2 (Merck) in a microwave digestion system (CEM, digestion procedures in Table 1) and diluted to 25 mL by adding double deionized water. Blank digestion was also conducted through the same method. During test, the concentrations of Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Pb, and U were analyzed using an Agilent 7500a ICP-MS system with 50 μg·L− 1 Li, Sc, Ge, Y, In, Tb, and Bi (Agilent Technologies, USA) added online as internal standards to correct for matrix effects and instrumental drift. During test, the accuracy of microwave digestion/ICP-MS method was verified by analysis of certified reference materials (GBW10050 GSB-28, IGGE, China). The reference substance of shrimp tissue (GBW10050 GSB-28, IGGE, China) was treated and analyzed in the same way as all samples. The analysis results (Al: 273.6 mg·kg− 1, V: 0.22 mg·kg− 1, Cr: 0.36 mg·kg− 1, Mn: 8.12 mg·kg− 1, Fe: 103 mg·kg− 1, Co: 0.05 mg·kg− 1, Ni: 0.242 mg·kg− 1, Cu: 10.08 mg·kg− 1, Zn: 71 mg·kg− 1, As: 2.76 mg·kg− 1, Se: 5.32 mg·kg− 1, Mo: 0.04 mg·kg− 1, Cd: 0.036 mg·kg− 1, Pb: 0.187 mg·kg− 1, and U:0.0089 mg·kg− 1) are consistent with the certified values (Al: 290.0 mg·kg− 1, V: 0.24 mg·kg− 1, Cr: 0.35 mg·kg− 1, Mn: 8.9 mg·kg− 1, Fe: 112 mg·kg− 1, Co: 0.044 mg·kg− 1, Ni: 0.23 mg·kg− 1, Cu: 10.3 mg·kg− 1, Zn: 76 mg·kg− 1, As: 2.5 mg·kg− 1, Se: 5.1 mg·kg− 1, Mo: 0.037 mg·kg− 1, Cd: 0.039 mg·kg− 1, Pb: 0.20 mg·kg− 1, and U: 0.0097 mg·kg− 1 of dry weight). The results for standard reference substance showed that element recovery ranged from 91.24% to 113.64% (n = 3). The standard deviation was less than 6%, proving the good repeatability of the methods. Information about trace element concentrations in fish species is important for both environmental management and human consumption. The concentrations of trace metals in fish species collected from the Spratly islands are illustrated in Table 2. The contents of trace metals in all fish samples were as follows: 0.045–6.393 mg·kg− 1 for Al, 0.040–3.312 mg·kg− 1 for V, 0.122–0.947 mg·kg− 1 for Cr, Table 1 The working parameters of microwave digestion. Stage
1 2 3 4
Power/W
Temperature
Ramp
Hold
Max
%
T/°C
t/min
t/min
1500 1500 1500 1500
100 100 100 100
100 150 170 190
3:00 7:00 5:00 5:00
3:00 3:00 3:00 10:00
2
Al
1.284 1.460 2.707 2.006 1.569 2.057 1.176 1.478 1.883 2.370 3.109 1.539 0.420 2.492 1.381 6.393 1.036 1.833 1.099 1.172 1.083 1.736 2.112 2.558 1.553 1.106 1.486 0.045 1.181 1.387 1.447 1.602 1.749 2.740 1.186 0.366 1.478 0.666 1.683 0.045 6.393
Fish species
Ostracion meleagris Cephalopholis argus Monotaxis grandoculis Balistapus undulatus Cephalopholis urodelus Kyphosus lembus Parupeneus multifasciatus Epinephelus merra Bloch Parupeneus pleurostigma Melichthys vidua Pervagor melanocephalus Cheilinus fasciatus Cheilinus rhodochrous Cephalopholis sonnerati Myrispristis pralinius Paraluteres prionurus Bleeker Odonus niger Cypselurus katoptron Heteropriaccmthuscruentatus Sufflamen fraenatus Gnathodentex aureolineatus Myrispristis Linnaeus Epinephelus hexagonatus Coris gaimard Scarus forsteri Diodon hystrix Aluterus scriptus Parupeneus trifasciatus Brittle star Epinephelus, groupers Lutjanus kasmira Cephalopholis urodelus Gymnothorax reticularis Bloch Gobiidae Platax teira Ctenochaetus striatus Halassoma quinquevittatus Mean concentration Min concentration Max concentration
Table 2 Concentrations of trace metals in fishes (mg·kg− 1).
0.083 0.097 0.327 0.116 0.079 0.082 0.132 0.705 0.083 0.643 1.675 0.270 0.180 0.184 0.064 1.649 0.074 0.040 0.066 0.835 0.219 0.103 0.082 0.062 0.092 0.081 0.205 0.071 0.049 0.704 0.048 0.052 0.057 0.103 3.312 0.062 0.064 0.536 0.350 0.040 3.312
V 0.343 0.508 0.388 0.326 0.358 0.276 0.292 0.352 0.375 0.636 0.947 0.285 0.253 0.415 0.373 0.305 0.371 0.372 0.667 0.337 0.358 0.794 0.344 0.252 0.414 0.279 0.378 0.204 0.411 0.132 0.297 0.365 0.417 0.233 0.242 0.169 0.343 0.122 0.367 0.122 0.947
Cr 0.647 0.371 2.193 3.223 0.734 0.350 1.350 2.430 0.649 7.071 5.158 10.960 1.780 0.966 0.505 11.740 4.075 1.001 1.045 0.598 0.719 1.121 1.827 1.014 1.472 2.845 2.020 0.450 0.581 14.300 0.565 1.496 0.587 5.838 10.380 0.373 1.421 8.390 2.954 0.350 14.300
Mn 18.670 20.780 49.360 43.850 24.610 23.060 37.630 29.240 33.240 33.230 67.780 51.100 15.890 36.650 21.660 125.600 34.200 35.390 19.160 23.580 25.740 30.700 52.920 50.080 27.050 24.290 27.340 13.400 20.080 30.770 25.860 21.360 26.170 146.700 51.880 14.500 26.640 31.200 36.615 13.400 146.700
Fe 0.110 0.010 0.022 0.045 0.019 0.022 0.070 0.115 0.032 0.091 0.177 0.394 0.041 0.030 0.019 0.129 0.024 0.023 0.007 0.020 0.019 0.115 0.388 0.033 0.058 0.096 0.057 0.015 0.020 0.458 0.028 0.084 0.017 0.032 0.260 0.014 0.071 0.134 0.087 0.007 0.458
Co 0.051 0.145 0.152 0.074 0.063 0.049 0.287 0.392 0.154 0.193 0.305 0.474 0.178 0.268 0.082 0.568 0.078 0.086 0.033 0.157 0.103 0.522 1.441 0.093 0.169 0.173 0.154 0.029 0.107 3.234 0.080 0.364 0.088 0.089 1.117 0.052 0.124 0.406 0.319 0.029 3.234
Ni 0.487 0.802 1.185 1.553 1.773 1.549 1.340 1.585 1.930 2.288 2.829 2.375 1.344 2.126 0.825 5.144 1.592 2.453 0.745 1.004 2.597 0.962 1.890 1.098 0.828 1.162 1.706 0.876 0.857 0.601 2.295 0.955 1.572 1.063 1.590 0.983 0.851 2.692 1.566 0.487 5.144
Cu 18.690 10.000 41.760 16.170 12.690 33.860 30.780 22.540 11.810 52.680 37.310 42.340 18.360 13.840 9.126 54.520 21.050 15.830 8.679 8.662 9.525 15.350 12.840 15.380 19.110 12.610 36.160 12.740 8.792 15.890 8.902 19.430 11.790 46.770 31.160 16.160 12.350 48.280 21.946 8.662 54.520
Zn 2.211 2.284 37.600 23.990 24.980 1.511 54.820 36.290 27.420 31.830 16.830 5.522 65.660 15.240 9.330 7.924 17.980 8.482 4.288 58.570 45.820 26.270 15.890 4.052 22.020 2.601 57.250 30.470 19.210 2.311 19.850 6.334 4.218 9.459 4.766 8.931 1.704 58.180 20.845 1.511 65.660
As 2.826 3.208 2.243 2.848 3.168 4.009 2.369 3.048 2.190 2.517 2.141 3.571 2.093 2.718 3.852 2.480 2.765 2.187 2.942 2.699 4.959 1.951 3.848 2.815 2.405 1.135 1.312 2.698 1.914 0.993 2.285 1.523 3.278 1.680 1.989 2.553 0.964 1.802 2.526 0.964 4.959
Se 0.168 0.709 8.538 0.180 27.290 0.046 15.500 0.772 0.088 0.072 0.634 0.253 0.263 0.141 5.522 0.455 0.490 0.041 0.561 9.967 39.420 0.592 0.505 0.171 1.148 0.435 0.933 0.235 0.539 1.226 5.482 0.027 11.610 0.517 0.340 0.549 0.664 0.054 3.583 0.027 39.420
Mo 0.021 0.029 0.033 0.037 0.231 0.016 0.110 0.272 0.126 0.329 0.424 0.452 0.077 0.333 0.048 1.061 0.102 0.082 0.012 0.045 0.046 0.316 0.429 0.337 0.078 0.047 0.202 0.002 0.030 1.301 0.366 0.022 0.037 0.072 0.281 0.008 0.076 1.066 0.225 0.002 1.301
Cd 0.024 0.024 0.357 0.038 0.065 0.039 0.090 0.255 0.052 0.077 0.382 0.156 0.026 0.183 0.061 0.769 0.026 0.055 0.022 0.043 0.037 0.348 0.236 0.156 0.077 0.051 0.060 0.012 0.025 0.463 0.355 0.067 0.081 0.355 0.223 0.067 0.101 0.086 0.146 0.012 0.769
Pb
0.053 0.053 0.057 0.051 0.053 0.053 0.063 0.015 0.053 0.058 0.079 0.008 0.010 0.061 0.053 0.014 0.052 0.051 0.052 0.052 0.052 0.068 0.058 < DL 0.063 0.060 0.053 < DL 0.051 0.415 0.054 0.058 0.052 < DL 0.127 < DL 0.066 0.016 0.061 < DL 0.415
U
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hydrochloric (0.05 mM HCl) acid solution was used for extracting inorganic arsenicals by using the method reported by Mir (Mir et al., 2007). Extraction efficiency was evaluated by calculating the ratio between total arsenic present in the extracts and the total arsenic present in the sample TORT-2 (Table 4). The extraction efficiencies obtained in this work were 95.51%, 93.75%, 94.05%, 90.32%, and 87.24% for As(V), MMA, DMA, AsB, and AsC, respectively. Fig. 4 shows the distribution characteristics of arsenic species in fishes. AsB exhibited the highest concentration and ratio among all arsenic species. Fifteen fish samples were selected and analyzed for their content of As species (Table 4). AsB was found to be the main arsenic species in all fish samples; this species (8.560 mg·kg− 1 to 31.020 mg·kg− 1) accounted for 31.48% to 47.24% of the total arsenic species. MMA and DMA were detected as minor compounds, with contents of 2.43%–12.56% and 3.42%–12.16%, respectively. The contents of MMA and DMA are higher than those of As(III) and As(V) in fish samples; this finding is consistent with those reported by other published studies. In the present study, high AsB concentration was found in C. rhodochrous sample (47.24%), and high MMA/DMA content was observed in Balistapus undulatus sample (12.56% and 12.16%). The inorganic arsenic was identified and quantified as As(III) and As (V). As(III) was found in 40% of all samples being not detected. As(V) in all fish samples was below 3.3% of the total arsenic. The low concentrations of inorganic arsenic in fish samples are consistent with the findings of previous studies (Larsen et al., 2005; Fontcuberta et al., 2011). In conclusion, this work described the determination and distribution characteristics of trace metals and arsenic species in tropical marine fishes collected from the Spratly islands. The metal contents are lower than the USEPA risk-based concentrations. In particular, the distribution ratios of Fe, Zn, and As in the fish samples are high. The selected heavy metals exhibit significant positive correlations, indicating similar source input in the region. Analysis of arsenic species showed that AsB was the main species in the fish samples; hence, arsenic toxicity in all fishes was small with high-total concentration. The results can provide initial data for environmental behavior study of trace metals and health assessment in tropical organisms.
Fig. 1. The distribution of trace metal in fishes.
min). This method optimized Brisbin's method and can completely separate As(III), As(V), DMA, and MMA, but not AsB and AsC. As shown in Fig. 3, As(III), As(V), DMA, MMA, AsB, and AsC can be completely separated within 15 min. The As concentrations in 15 fishes of 38 samples are higher than 20.0 mg·kg− 1 (Table 4). The high As concentration in fishes may cause health hazards, although As usually exists in living organisms in different forms. As species show different levels of toxicity in the following order: As(V) > As(III) > (MMA) > (DMA) > (AsC) > (AsB), with LD50 values of 14, 20, 700–1800, 700–2600, 6500, and > 10,000) mg·kg− 1, respectively, in rats. The USEPA (USEPA, 2000) also advocated inorganic As uptake, instead of total As exposure, for assessment of human health risk. Inorganic As represented a minimal portion, accounting for less than 10% of total As in most cases (Huang et al., 2003). Hence, individual arsenic species must be considered to accurately evaluate their risk profiles. Thus, analysis of As species in marine organisms is important. The content and distribution of arsenic species in 15 fishes were analyzed. First, a sequential extraction procedure was used to fractionate arsenic compounds in dry fish samples. Other researchers usually ignored nonpolar arsenicals because of their low concentrations. In the present study, acetone exhibited the optimal performance in step I and was chosen as solvent in further experiments. The methanol or its water solution was the appropriate choice for water-soluble arsenicals in step II. In the last step, the diluted
Acknowledgements The authors gratefully acknowledge the Basic Scientific Fund for National Public Research Institutes of China (2016Q02 & 2017Q09) and The National Natural Science Foundation of China-Shandong Joint Funded Project (U1406403). C. Sun would also like to thank Taishan Scholar for funding support. Fig. 2. The comparison of the relative content of heavy metals.
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Table 3 The correlation coefficient of trace metal in fishes.
Al V Cr Mn Fe Co Ni Cu Zn As Se Mo Cd Pb U
Al
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
As
Se
Mo
Cd
Pb
U
1.000
0.310 1.000
0.237 0.073 1.000
0.347 0.610 (0.193) 1.000
0.749 0.355 (0.015) 0.501 1.000
0.100 0.393 (0.117) 0.718 0.201 1.000
0.065 0.350 (0.207) 0.648 0.111 0.830 1.000
0.650 0.386 0.066 0.417 0.488 0.141 (0.015) 1.000
0.502 0.410 (0.007) 0.625 0.612 0.244 0.045 0.521 1.000
(0.252) (0.027) (0.057) (0.127) (0.168) (0.198) (0.159) 0.121 0.156 1.000
0.007 (0.147) 0.063 (0.277) (0.112) (0.109) (0.239) 0.164 (0.166) (0.021) 1.000
(0.107) (0.090) (0.028) (0.224) (0.124) (0.211) (0.126) 0.121 (0.201) 0.325 0.471 1.000
0.385 0.389 (0.170) 0.780 0.337 0.648 0.698 0.505 0.416 0.003 (0.233) (0.147) 1.000
0.734 0.462 0.073 0.580 0.697 0.428 0.475 0.502 0.445 (0.167) (0.219) (0.126) 0.664 1.000
(0.087) 0.207 (0.164) 0.461 (0.055) 0.529 0.852 (0.291) (0.139) (0.260) (0.345) (0.040) 0.466 0.300 1.000
Note: “( )” mean negative correlation.
Fig. 3. The separation of arsenic species standard (10 μg/L AsC, AsB, AsIII, DMA, MMA and AsV mix solution).
Table 4 The concentration of arsenic species in different fish (mg·kg− 1, dry weight). Sample name TORT-2
Total As
As(III)
As(V)
MMA
DMA
AsB
AsC
a
21.6 ± 1.8
0.024 ± 0.010
14.25 ± 1.08
0.0928 ± 0.0371
0.84 ± 0.10
0.093 ± 0.069
0.0928 ± 0.0371
b
20.4 ± 1.3
ND
13.61 ± 1.05
0.087 ± 0.014
0.79 ± 0.21
0.084 ± 0.03
0.0807 ± 0.023
94.44
ND
95.51
93.75
94.05
90.32
87.24
22.02 23.99 24.98 26.27 27.42 30.47 31.83 36.29 37.60 45.82 54.82 57.25 58.18 58.57 65.66
ND ND ND ND ND 0.011 0.015 0.020 ND 0.031 0.029 0.018 0.090 0.018 0.022
0.560 0.432 0.212 0.185 0.110 0.301 0.410 0.201 0.289 1.011 1.211 0.895 0.932 0.247 0.331
2.360 3.012 2.220 1.960 3.230 1.965 2.011 1.656 0.995 2.831 3.010 2.089 1.977 1.423 4.012
2.101 2.916 1.987 2.031 2.590 2.461 2.236 2.011 1.985 3.004 3.612 2.886 2.501 2.005 3.678
8.560 9.231 10.011 11.320 9.650 10.988 10.021 12.110 14.530 15.091 21.360 24.025 25.371 26.003 31.020
0.240 0.307 ND ND ND ND ND ND ND 0.985 1.013 0.889 1.022 0.961 1.009
Reference Measured
Recovery (%) Coris gaimard Balistapus undulatus Cephalopholis urodelus Myrispristis Parupeneus pleurostigma Aluterus scriptus Melichthys vidua Epinephelus merra Bloch Monotaxis grandoculis Gnathodentex aureolineatus Parupeneus multifasciatus Diodon hystrix Halassoma quinquevittatus Sufflamen fraenatus Cheilinus rhodochrous a b
These were reference value given by Raimund Wahlen (Wahlen and McSheehy, 2004). Determination of arsenic species by HPLC-ICP-MS in the study.
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Fig. 4. The analysis of arsenic species in fishes.
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